SortaGrey

Recently bought a 63cm 3.0 frame circa '90 that arrived with 120 spacing.. serial number sez 126 spacing. Can't see any damage.. or toe in of these cantilever rears. Appears the rear hanger has been replaced... has a plate seemingly attaching this new fixture. Possibly this is how the frame was made... ?

I could live with a 120.. I build my own wheels.. .that is doable.. an interesting challenge. I've been high and low regarding opines on how to proceed moving it back to 126... 'just slide a 126 in there and run it'... which can be done with thumb pressure. I can also slide a 130 with "firmer" thumb pressure. One suggestion was a jig.. some type of restriction on the rear triangle to prevent any outward or inward movement of that triangle.. these cantilever rears place the axle around 1.5" behind that triangle intersection. Then a turnbuckle like arrangement to move this spacing out with controlled pressure.. "just enough".

My only reason for considering a chg of this now 120 spacing is the feature of the axle being well behind said triangle intersection. One reads a pile of regurgitated aluminum resetting 'views' on the net.. those pts taken. I was hoping to get some input from knowledgeable frame builders.........

PITA to have to struggle with a sticky rear chging out a tire.. espechially on the road. Guess my prime reason for considering chging it out.

Thanks.

Homebrew01

I have several Cannondales around that age, and they should be 126. I didn't actually measure mine, but I just jam in 130 mm wheels and ride. I don't swap wheels often enough that it matters to me about the extra "oomph" to get a wheel in.

GrayJay

I think the C-dale frames of that time were built with 128mm spacing so that either a 7 or 8 speed wheel could be used with just minimal prying of the stays in either direction. If it now has 120mm spacing, that frame is terminally damaged. Cold setting (bending) heat treated aluminum makes it too brittle, you simply cannot cold-set a aluminum frame like you can a CrMo frame and expect it to hold up. I would return it to the seller if at all possible and tell them to cut it up, it is not safe and not salvageable.

SortaGrey

"I think the C-dale frames of that time were built with 128mm spacing"

Clearly my post states serial # info declares 126 spacing.

Another variable. Appears to me a new plate was attached gear side for a new hanger.. this takes ~1.5mm inside with. So my 'cold setting' if that is indeed the issue.. is around 4.5mm. And to note.. no cold setting outward has taken place to date. Given 'dale did issue 128's with the idea of going 130 or 126.. seems to me the actual strain.. if that is the right term.. to this rear is minimal.

I'd guess.. someone ran a 120 fixie in there. Or.. it came this way.. I hear that did happen.

Be interesting.. to have someone measure a identical frame.. inside the rear triangle just forward of the weld joint that attaches to the rear axle tab. But that measurement would have to be in thousandth's.. doable with a a good dial caliper. [ NOTE: measures 4.060" just where the tube goes 'full round' ]

Homebrew01

I don't quite know what you're measuring. It's too variable with the chainstays at an angle to get a meaningful comparison.
Mine comes out right at 126mm (4.965 inches) inside the dropouts just above where the locknuts marks are.

How about some pictures ? 120mm is not right. Do you get 120mm at all areas of the dropout, or is one maybe bent in so they're not parallel ?
Those rear triangles are not easily deformed.

SortaGrey

I'm going to build a 123 rear width.. using an OC rim.. I wanted to work with an OC for some time. 123 as that about comes out nearly a symmetrical rear using a 6 sp setup.

Seller does not respond to polite inquiry as to this frame's history. I seriously doubt he knew anything per that measurement.. just flipped a frame he scored.

SortaGrey

https://i42.tinypic.com/2ueics9.jpg

OK.. pic of this rear.. in a collage. Suggest not reading anything into the camera angles.. it's as square as I can tell by eye or caliper.

Had a 127.5 spacing sitting here via this hub.. in the pic link shown mounting in the rear.

My data input into MACHINE HEAD software.. per a near symmetrical rear: https://i43.tinypic.com/1osqwk.jpg NOTE.. the tension L to R shows the NDS higher
than the DS.. this due I suspect per 130 spacing wired into the software program... vs the 127.5 I used for this scenario.

I'll set the OC 6 speed setup at 123.5 width.. giving near the same result as shown via Machine Head. Only a 6'er.. I thought I'd need more until I tried that set out last summer.. really nice for 'silver hairs'.. 14-15-17-20-24-28 is going on. Last summer a 42/26 got my 1/4+ mile hill done-- around a 16% grade overall.. . Considering a 44-46/34 compact...

EnzoRWD

Be careful with that frame. Those Cannondales are pretty old these days. I had a 3.0 that was spread to ~128mm when I received it, probably from running 130mm wheels. I was building it with 126mm spacing and clamped a wheel in during the building process. When I released the QR an hour later, the chainstay cracked. I was pissed, but it very well could have happened on my first ride.

I have an unreasonable fetish for the old Cannondales and Kleins, but old aluminum should be treated with care and inspected for signs of stress cracking (usually feathering or lifting paint).

ftwelder

Could it be that the hanger doesn't belong or has been adapted from another model?

Many Cannondale frames have severe undercut in the weld areas. I know they are great bikes and people love them etc. but it increases the chance of having an issue when bending the frame. Trying to use a wheel that is too wide for current spacing will cause the dropouts to wear quickly.

SortaGrey

No.. seems this hanger is original.

Yes.. I do agree. Built a 126 just for this rear.. very minor spreading inserting. For me running a larger width spacing is just asking for trouble. Don't like road rash........

ftwelder

Clearly, you are an individual with excellent judgement!